Composition for Odor Suppression

ABSTRACT

A composition for odor control includes (A) from 85 wt % to 99.5 wt % of an olefin-based compound and (B) from 15 wt % to 0.5 wt % of an odor suppressant. The odor suppressant includes a blend of (i) an ionomer, (ii) particles of zinc oxide, and (iii) particles of copper oxide. The composition has a methyl mercaptan odor suppression value of greater than 45% as measured in accordance with ASTM D5504-12.

BACKGROUND

Many uses of articles made from olefin-based polymer encounter the nuisance of foul odor. Common sources of offending odor include hydrogen sulfide (H₂S) emitting compositions and mercaptan-containing compositions. Many applications exist where it is desirable for an olefin-based polymer article to be able to remove, or otherwise suppress, odor. As such, numerous industries desire materials that can remove sulfur-based odorants such as H₂S and mercaptans, from the gas phase. A common example is the ability of a plastic trash bag liner (i.e., an olefin-based polymer article) to be able to remove odor.

Metal oxides such as zinc oxide (ZnO) particles, and zinc salts in particular, are known to consume many odor-generating molecules such as H₂S and mercaptans. All other factors being equal, it is known that ZnO concentration and odor suppression are directly related—i.e., as ZnO concentration increases in a given olefin-based polymer article, the effectiveness of odor suppression also increases.

Although odor suppression increases as metal oxide (ZnO in particular) increases, limits do exist for the amount of ZnO that can be effectively incorporated into olefin-based polymer articles. In the production of blown film trash liners for example, high loading of ZnO particles increases extrusion die lip buildup, thereby causing film defects. High loading of ZnO particles also increases haze resulting in degradation of olefin-based polymer film transparency and/or degradation in film color. High loading of ZnO particles also deleteriously impacts mechanical properties such as impact strength and film tear strength. Processing parameters and end-use mechanical requirements thereby impose practical limits to the load of ZnO particles into olefin-based polymer compositions.

A need therefore exists for olefin-based polymer compositions with improved odor suppression while simultaneously carrying suitable metal and/or zinc load in order to maintain processability, desired optics, and desired mechanical properties for end-use applications. A need further exists for odor-suppressing articles made from such olefin-based polymer compositions.

SUMMARY

The present disclosure provides a composition. In an embodiment, a composition for odor control is provided and includes (A) from 85 wt % to 99.5 wt % of an olefin-based compound and (B) from 15 wt % to 0.5 wt % of an odor suppressant. The odor suppressant includes a blend of (i) an ionomer, (ii) particles of zinc oxide, and (iii) particles of copper oxide. The composition has a methyl mercaptan odor suppression value of greater than 45% as measured in accordance with ASTM D5504-12.

Definitions

Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc., 1990-1991. Reference to a group of elements in this table is by the new notation for numbering groups.

For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent U.S. version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.

The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., 1 or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., the range 1-7 above includes subranges of 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.

An “agglomerate” is a plurality of individual fine solid particles clumped or otherwise together forming a single mass.

The terms “blend” or “polymer blend,” as used herein, is a blend of two or more polymers. Such a blend may or may not be miscible (not phase separated at molecular level). Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art.

The term “composition” refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

The terms “comprising,” “including,” “having” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step, or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step, or procedure not specifically delineated or listed. The term “or,” unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

An “ethylene-based polymer” is a polymer that contains more than 50 weight percent (wt %) polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylene homopolymer, and ethylene copolymer (meaning units derived from ethylene and one or more comonomers). The terms “ethylene-based polymer” and “polyethylene” may be used interchangeably. Non-limiting examples of ethylene-based polymer (polyethylene) include low density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra-low density polyethylene (ULDPE), very low density polyethylene (VLDPE), multi-component ethylene-based copolymer (EPE), ethylene/α-olefin multi-block copolymers (also known as olefin block copolymer (OBC)), substantially linear, or linear, plastomers/elastomers, and high density polyethylene (HDPE). Generally, polyethylene may be produced in gas-phase, fluidized bed reactors, liquid phase slurry process reactors, or liquid phase solution process reactors, using a heterogeneous catalyst system, such as Ziegler-Natta catalyst, a homogeneous catalyst system, comprising Group 4 transition metals and ligand structures such as metallocene, non-metallocene metal-centered, heteroaryl, heterovalent aryloxyether, phosphinimine, and others. Combinations of heterogeneous and/or homogeneous catalysts also may be used in either single reactor or dual reactor configurations.

“Ethylene plastomers/elastomers” are substantially linear, or linear, ethylene/α-olefin copolymers containing homogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C₃-C₁₀ α-olefin comonomer. Ethylene plastomers/elastomers have a density from 0.870 g/cc to 0.917 g/cc. Non-limiting examples of ethylene plastomers/elastomers include AFFINITY™ plastomers and elastomers (available from The Dow Chemical Company), EXACT™ Plastomers (available from ExxonMobil Chemical), Tafmer™ (available from Mitsui), Nexlene™ (available from SK Chemicals Co.), and Lucene™ (available LG Chem Ltd.).

“High density polyethylene” (or “HDPE”) is an ethylene homopolymer or an ethylene/α-olefin copolymer with at least one C₄-C₁₀ α-olefin comonomer, or C₄-C₈ α-olefin comonomer and a density from 0.940 g/cc, or 0.945 g/cc, or 0.950 g/cc, 0.953 g/cc to 0.955 g/cc, or 0.960 g/cc, or 0.965 g/cc, or 0.970 g/cc, or 0.975 g/cc, or 0.980 g/cc. The HDPE can be a monomodal copolymer or a multimodal copolymer. A “monomodal ethylene copolymer” is an ethylene/C₄-C₁₀ α-olefin copolymer that has one distinct peak in a gel permeation chromatography (GPC) showing the molecular weight distribution. A “multimodal ethylene copolymer” is an ethylene/C₄-C₁₀ α-olefin copolymer that has at least two distinct peaks in a GPC showing the molecular weight distribution. Multimodal includes copolymer having two peaks (bimodal) as well as copolymer having more than two peaks. Non-limiting examples of HDPE include DOW™ High Density Polyethylene (HDPE) Resins (available from The Dow Chemical Company), ELITE™ Enhanced Polyethylene Resins (available from The Dow Chemical Company), CONTINUUM™ Bimodal Polyethylene Resins (available from The Dow Chemical Company), LUPOLEN™ (available from LyondellBasell), as well as HDPE products from Borealis, Ineos, and ExxonMobil.

An “interpolymer” is a polymer prepared by the polymerization of at least two different monomers. This generic term includes copolymers, usually employed to refer to polymers prepared from two different monomers, and polymers prepared from more than two different monomers, e.g., terpolymers, tetrapolymers, etc.

“Linear low density polyethylene” (or “LLDPE”) is a linear ethylene/α-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C₃-C₁₀ α-olefin, or C₄-C₈ α-olefin, comonomer. LLDPE is characterized by little, if any, long chain branching, in contrast to conventional LDPE. LLDPE has a density from 0.910 g/cc to less than 0.940 g/cc. Non-limiting examples of LLDPE include TUFLIN™ linear low density polyethylene resins (available from The Dow Chemical Company), DOWLEX™ polyethylene resins (available from the Dow Chemical Company), and MARLEX™ polyethylene (available from Chevron Phillips).

“Low density polyethylene” (or “LDPE”) consists of ethylene homopolymer, or ethylene/α-olefin copolymer comprising at least one C₃-C₁₀ α-olefin, or C₄-C₈ α-olefin, that has a density from 0.915 g/cc to less than 0.940 g/cc and contains long chain branching with broad MWD. LDPE is typically produced by way of high pressure free radical polymerization (tubular reactor or autoclave with free radical initiator). Non-limiting examples of LDPE include MarFlex™ (Chevron Phillips), LUPOLEN™ (LyondellBasell), as well as LDPE products from Borealis, Ineos, ExxonMobil, and others.

“Multi-component ethylene-based copolymer” (or “EPE”) comprises units derived from ethylene and units derived from at least one C₃-C₁₀ α-olefin, or C₄-C₈ α-olefin, comonomer, such as described in patent references U.S. Pat. Nos. 6,111,023; 5,677,383; and 6,984,695. EPE resins have a density from 0.905 g/cc to 0.962 g/cc. Non-limiting examples of EPE resins include ELITE™ enhanced polyethylene (available from The Dow Chemical Company), ELITE AT™ advanced technology resins (available from The Dow Chemical Company), SURPASS™ Polyethylene (PE) Resins (available from Nova Chemicals), and SMART™ (available from SK Chemicals Co.).

An “olefin-based polymer” or “polyolefin” is a polymer that contains more than 50 weight percent polymerized olefin monomer (based on total amount of polymerizable monomers), and optionally, may contain at least one comonomer. Non-limiting examples of an olefin-based polymer include ethylene-based polymer or propylene-based polymer.

A “polymer” is a compound prepared by polymerizing monomers, whether of the same or a different type, that in polymerized form provide the multiple and/or repeating “units” or “mer units” that make up a polymer. The generic term polymer thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one type of monomer, and the term copolymer, usually employed to refer to polymers prepared from at least two types of monomers. It also embraces all forms of copolymer, e.g., random, block, etc. The terms “ethylene/α-olefin polymer” and “propylene/α-olefin polymer” are indicative of copolymer as described above prepared from polymerizing ethylene or propylene respectively and one or more additional, polymerizable α-olefin monomer. It is noted that although a polymer is often referred to as being “made of” one or more specified monomers, “based on” a specified monomer or monomer type, “containing” a specified monomer content, or the like, in this context the term “monomer” is understood to be referring to the polymerized remnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to has being based on “units” that are the polymerized form of a corresponding monomer.

A “propylene-based polymer” is a polymer that contains more than 50 weight percent polymerized propylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Propylene-based polymer includes propylene homopolymer, and propylene copolymer (meaning units derived from propylene and one or more comonomers). The terms “propylene-based polymer” and “polypropylene” may be used interchangeably. Non-limiting examples of suitable propylene copolymer include propylene impact copolymer and propylene random copolymer.

“Ultra-low density polyethylene” (or “ULDPE”) and “very low density polyethylene” (or “VLDPE”) each is a linear ethylene/α-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C₃-C₁₀ α-olefin comonomer. ULDPE and VLDPE each has a density from 0.885 g/cc to 0.915 g/cc. Non-limiting examples of ULDPE and VLDPE include ATTANE™ ultra low density polyethylene resins (available from The Dow Chemical Company) and FLEXOMER™ very low density polyethylene resins (available from The Dow Chemical Company).

Test Methods

D10, D50, and D90 particle size is measured using a Coulter LS 230 Laser Light Scattering Particle Sizer, available from Coulter Corporation. D10 particle size is the particle diameter at which 10% of the powder's mass is composed of particles with a diameter less than this value. D50 particle size is the particle diameter at which 50% of the powder's mass is composed of particles with a diameter less than this value and 50% of the powder's mass is composed of particles with a diameter greater than said value. D90 particle size is the particle diameter at which 90% of the powder's mass is composed of particles with a diameter less than this value. Mean volume average particle size is measured using a Coulter LS 230 Laser Light Scattering Particle Sizer, available from Coulter Corporation. Particle size distribution is calculated in accordance with Equation A:

$\begin{matrix} {{Particle}\mspace{14mu}{size}\mspace{14mu}{distribution}{{= \frac{\left( {{D90} - {D10}} \right)}{D50}}.}} & {{Equation}\mspace{14mu} A} \end{matrix}$

Dart impact strength is measured in accordance with ASTM D1709, with results reported in grams (g).

Density is measured in accordance with ASTM D792, Method B. The result is recorded in grams per cubic centimeter (g/cc).

Differential Scanning Calorimetry (DSC). Differential Scanning Calorimetry (DSC) can be used to measure the melting, crystallization, and glass transition behavior of a polymer over a wide range of temperature. For example, the TA Instruments Q1000 DSC, equipped with an RCS (refrigerated cooling system) and an autosampler is used to perform this analysis. During testing, a nitrogen purge gas flow of 50 ml/min is used. Each sample is melt pressed into a thin film at about 175° C.; the melted sample is then air-cooled to room temperature (about 25° C.). A 3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer, weighed, placed in a light aluminum pan (ca 50 mg), and crimped shut. Analysis is then performed to determine its thermal properties.

The thermal behavior of the sample is determined by ramping the sample temperature up and down to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180° C. and held isothermal for 3 minutes in order to remove its thermal history. Next, the sample is cooled to −40° C. at a 10° C./minute cooling rate and held isothermal at −40° C. for 3 minutes. The sample is then heated to 180° C. (this is the “second heat” ramp) at a 10° C./minute heating rate. The cooling and second heating curves are recorded. The cool curve is analyzed by setting baseline endpoints from the beginning of crystallization to −20° C. The heat curve is analyzed by setting baseline endpoints from −20° C. to the end of melt. The values determined are extrapolated onset of melting, Tm, and extrapolated onset of crystallization, Tc. Heat of fusion (H_(f)) (in Joules per gram), and the calculated % crystallinity for polyethylene samples using the following Equation: % Crystallinity=((H_(f))/292 J/g)×100. Glass transition temperature, Tg, is determined from the DSC heating curve where half the sample has gained the liquid heat capacity as described in Bernhard Wunderlich, The Basis of Thermal Analysis, in Thermal Characterization of Polymeric Materials 92, 278-279 (Edith A. Turi ed., 2d ed. 1997). Baselines are drawn from below and above the glass transition region and extrapolated through the Tg region. The temperature at which the sample heat capacity is half-way between these baselines is the Tg.

Elmendorf tear (or tear) is measured in accordance with ASTM D1922-15, machine direction (MD), with results reported in grams-force (gf).

Melt flow rate (MFR) in g/10 min is measured in accordance with ASTM D1238 (230° C./2.16 kg).

Melt index (MI) (12) in g/10 min is measured in accordance with ASTM D1238 (190° C./2.16 kg).

Odor Suppression/Odor Suppression Value.

Odor suppression is the ability of a composition to neutralize, or otherwise reduce, the amount of volatile sulfur-containing compounds. In the present disclosure, the odor suppression for methyl mercaptan is measured with gas chromatography equipped with an Agilent Sulfur Chemiluminescence Detector (GC-SCD) in accordance with ASTM D5504-12. A control sample is prepared by placing a film formed from DOWLEX 2085G, ethylene/octene LLDPE, into a Tedlar® bag (polyvinyl fluoride). The Tedlar® bag for the control is subsequently filled with 900 mL of helium gas and known amount of methyl mercaptan and the Tedlar® bag is closed. Test samples are prepared by placing a film formed from respective test compositions, each test film placed into a respective Tedlar® bag. Each Tedlar® bag is subsequently filled with 900 mL of helium gas and known amount of methyl mercaptan, and the Tedlar® bag is closed. Samples are injected onto the GC-SCD at pre-determined time intervals from each bag in order to evaluate odor suppression capability.

The reference samples and test samples were analyzed after two days. The reference sample was used as the calibration standard to calculate the methyl mercaptan concentration of each test sample.

A. Sample Preparation

The control sample and each test sample containing 5 ppmv methyl mercaptan were prepared in SKC 1 L sample bag (SKC Tedlar® Sample Bag, 1 Liter, Cat No. 232-01). A reference sample without a film was prepared in a Tedlar® bag as the calibration standard.

1. Cut 1.0 g of film into strips (approximately 1 cm×30 cm). 2. Unscrew the valve from the sample bag, insert the film strips into the bag through the valve opening with the handle of cotton tipped applicator, and install the valve back to the sample bag, squeeze air out of bag before tightening the valve to seal the bag. 3. Fill the bag with 0.90 L of helium gas (AirGas, Ultra Grade Helium). 4. Inject 50 mL of 100 ppmv methyl mercaptan, into the bag using a gas-tight glass syringe.

The odor suppression value test can also be performed for other odorants, including ethyl mercaptan, propyl mercaptan, and butyl mercaptan.

B. GC-SCD Conditions

-   -   1 Gas chromatograph: Agilent Model 7890 with a split/splitless         injection port, available from Agilent Technologies, 2850         Centerville Road, Wilmington, Del. 19808.     -   2. Detector: Agilent Sulfur Chemiluminescence (SCD), Model         G6644A.     -   3. Chromatography data system: Agilent OpenLAB software.     -   4. Columns: Agilent J&W DB-1 30 m×0.32 mm ID, 5 μm film         thickness.     -   5. Carrier Gas: Hydrogen, constant flow mode, 2.0 ml/min.     -   6. Inlet: Split, temperature: 250° C., split ratio: 100:1.     -   7. Injection volume: 500 μL by Valco Six Port Valve, Loop Size:         500 μL.     -   8. Oven Temperature: 30° C. hold for 1 minute, 15° C./min to         140° C., hold for 1 minutes.     -   9. SCD Detector Conditions:     -   Temperature: 250° C.     -   Hydrogen Flow: 38.3 mL/min.     -   Oxidizer Flow: 59.9 sccm.     -   Pressure: 400 Torr.     -   An odor suppression value (OSV) is the removal % of methyl         mercaptan calculated by the following equation:

${OSV} = {{\frac{\begin{matrix} {{{Concentration}\mspace{14mu}{of}\mspace{14mu}{Reference}\mspace{14mu}{Sample}} -} \\ {{Concentration}\mspace{14mu}{of}\mspace{14mu}{Test}\mspace{14mu}{Sample}} \end{matrix}}{{Concentration}\mspace{14mu}{of}\mspace{14mu}{Reference}\mspace{14mu}{Sample}} \times 100} = {\frac{\begin{matrix} {{{Peak}\mspace{14mu}{Area}\mspace{14mu}{of}\mspace{14mu}{Reference}\mspace{14mu}{Sample}} -} \\ {{Peak}\mspace{14mu}{Area}\mspace{14mu}{of}\mspace{14mu}{Test}\mspace{14mu}{Sample}} \end{matrix}}{{Peak}\mspace{14mu}{Area}\mspace{14mu}{of}\mspace{14mu}{Reference}\mspace{14mu}{Sample}} \times 100}}$

The Peak Area is the response of GC-SCD.

A non-limiting example of OSV calculation is provided. At two days the GC-SCD peak area of methylmercaptan in the reference sample is 28240298, whereas the GC-SCD peak area of methyl mercaptan in the test sample IE 1 is 5667327 (unit is pA*s in Agilent OpenLAB software). The odor suppression value for the test sample IE 1 is (((28240298-5667327)/28240298)*100=80. As shown in the equation of OSV, both concentration of methyl mercaptan and GC-SCD Peak Area of methyl mercaptan can be used to calculate OSV.

Porosity and Surface Area. Brunauer-Emmett-Teller (BET) porosity and surface area analysis are performed using a Micromeritics Accelerated Surface Area & Porosimetry instrument (ASAP 2420). The sample is out-gassed at 105° C. while under vacuum prior to analysis.

The ASAP 2420 instrument employs a static (volumetric) method of dosing samples and measures the quantity of gas that can be physically adsorbed (physisorbed) on a solid at liquid nitrogen temperature. For the multi-point BET measurement the volume of nitrogen uptake is measured at pre-selected relative pressure points at constant temperature. The relative pressure is the ratio of the applied nitrogen pressure to the vapor pressure of nitrogen at the analysis temperature of 77 Kelvin (K). Results for porosity are reported in cubic meters per gram, or m³/g. Results for surface area are reported in square meters per gram, or m²/g.

Zinc/copper-total amount. The total amount of zinc and/or copper present in a composition is determined with x-ray fluorescence spectrometry (XRS), in accordance with ASTM D6247. Results are reported in parts per million, or ppm.

DETAILED DESCRIPTION

The present disclosure provides a composition. In an embodiment, a composition for suppressing odors is provided and includes (A) from 85 wt % to 99.5 wt % of an olefin-based polymer and (B) from 15 wt % to 0.5 wt % of an odor suppressant. The odor suppressant is a blend composed of (Bi) an ionomer, (Bii) particles of zinc oxide, and (Biii) particles of copper oxide. The composition has a methyl mercaptan odor suppression value of greater than 45% as measured in accordance with ASTM D5504-12.

A. Olefin-Based Polymer

The present composition includes an olefin-based polymer. The olefin-based polymer can be a propylene-based polymer or an ethylene-based polymer. Non-limiting examples of propylene-based polymer include propylene copolymer, propylene homopolymer, and combinations thereof. In an embodiment, the propylene-based polymer is a propylene/α-olefin copolymer. Non-limiting examples of suitable α-olefins include C₂ and C₄-C₂₀ α-olefins, or C₄-C₁₀ α-olefins, or C₄-C₈ α-olefins. Representative α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene.

In an embodiment, the propylene/α-olefin copolymer is a propylene/ethylene copolymer containing greater than 50 wt % units derived from propylene, or from 51 wt %, or 55 wt %, or 60 wt % to 70 wt %, or 80 wt %, or 90 wt %, or 95 wt %, or 99 wt % units derived from propylene, based on the weight of the propylene/ethylene copolymer. The propylene/ethylene copolymer contains a reciprocal amount of units derived from ethylene, or from less than 50 wt %, or 49 wt %, or 45 wt %, or 40 wt % to 30 wt %, or 20 wt %, or 10 wt %, or 5 wt %, or 1 wt % units derived from ethylene, based on the weight of the propylene/ethylene copolymer.

In an embodiment, the olefin-based polymer is an ethylene-based polymer. The ethylene-based polymer can be an ethylene homopolymer or an ethylene/α-olefin copolymer.

In an embodiment, the ethylene-based polymer is an ethylene/α-olefin copolymer. Non-limiting examples of suitable α-olefins include C₃-C₂₀ α-olefins, or C₄-C₁₀ α-olefins, or C₄-C₈ α-olefins. Representative α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene.

In an embodiment, the ethylene/α-olefin copolymer is an LLDPE that is an ethylene/C₄-C₈ α-olefin copolymer. The LLDPE has one, some, or all of the following properties:

(i) a density from 0.910 g/cc to 0.930 g/cc, or from 0.915 g/cc to 0.926 g/cc; and/or

(ii) a melt index from 0.5 g/10 min, or 1.0 g/10 min, or 2.0 g/10 min to 3.0 g/10 min, or 4.0 g/10 min, or 5.0 g/10 min.

B. Odor Suppressant

The present composition includes an odor suppressant. The odor suppressant is composed of a (Bi) an ionomer, (Bii) particles of zinc oxide, and (Biii) particles of copper oxide.

(Bi) Ionomer

The present composition includes an ionomer. An “ionomer,” as used herein, is an ion-containing polymer. An “ion” is an atom that has an electrical charge, either positive or negative. The ionomer has a majority weight percent (generally 85% to 90%) of repeating monomer units that are non-ionic (non-polar), and a minority weight percent (generally 10% to 15%) of repeating comonomer units that are ionic, or polar (i.e., positively-charged or negatively-charged). The positive charges of the ionic groups attract the negative charges of the ionic groups, creating ionic bonds. Ionomer resins exhibit what is known as “reversible crosslinking” behavior, i.e. when an ionomer is heated, the polymer chains have increased mobility, and the ionic bonds cannot stay intact because the positive charges and negative charges are pulled away from each other.

Non-limiting examples of the monomers and comonomers from which an ionomer is derived include a copolymer of at least one alpha-olefin and at least one ethylenically unsaturated carboxylic acid and/or anhydride. Non-limiting examples of suitable alpha-olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 3-methylbutene. Non-limiting examples of suitable carboxylic acids and anhydrides include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, and maleic anhydride.

In an embodiment, the ionomer is a copolymer of ethylene and methacrylic acid.

In an embodiment, the ionomer is a copolymer of ethylene and acrylic acid.

In an embodiment, the ionomer is a metal ionomer. A “metal ionomer,” as used herein, refers to a copolymer based on a metal salt of a copolymer of an alpha-olefin and an ethylenically unsaturated carboxylic acid and/or anhydride. The metal ionomer may be fully or partially neutralized by a metal ion. Non-limiting examples of metals suitable for neutralizing an ionomer include the alkali metals, i.e., cations such as sodium, lithium, and potassium; alkaline earth metals, i.e., cations such as calcium, magnesium; and transition metals such as zinc. A non-limiting example of a metal ionomer is Surlyn® 8660, which is a sodium salt of an ethylene and methacrylic acid copolymer, available from Dow-DuPont.

In an embodiment, the metal ionomer is a zinc ionomer. The term “zinc ionomer,” (or “ZnI/O”) as used herein, refers to a copolymer based on a zinc salt of a copolymer of ethylene and a vinyl comonomer with carboxylic acid/or anhydride. Non-limiting examples of suitable comonomer having vinyl comonomer with an acid group include methyl/methacrylic acid, vinyl acrylic acid, methacrylate, n-butyl acrylic acid, and acrylic acid.

Non-limiting examples of suitable zinc ionomer include zinc salt of ethylene/acrylic acid comonomer, zinc salt of ethylene/methyl-methacrylic acid copolymer, zinc salt of ethylene/vinyl acrylic acid copolymer, zinc salt of ethylene/methacrylate copolymer, zinc salt of ethylene/n-butyl acrylic acid copolymer, and any combination thereof.

In an embodiment, the zinc ionomer is a zinc salt of ethylene/acrylic acid copolymer. Non-limiting examples of a suitable zinc ionomer include Surlyn® 9150, which is a zinc salt of an ethylene and methacrylic acid copolymer, available from Dow-DuPont.

B(ii) Particles of Zinc Oxide

The odor suppressant includes particles of zinc oxide (or “ZnO”). The ZnO particles have a D50 particle size from 100 nm to 3000 nm, a surface area from 1 m²/g to less than 10 m²/g, and a porosity less than 0.020 m³/g.

In an embodiment, the ZnO particles have one, some, or all of the following properties (i)-(iii) below:

(i) a particle size D50 from 100 nm, or 200 nm, or 300 nm, or 400 nm to 500 nm, or 600 nm, or 700 nm, or 800 nm, or 900 nm, or 1000 nm, or 2000 nm, or 3000 nm; and/or

(ii) a surface area from 1 m²/g, or 2 m²/g, or 3 m²/g, or 4 m²/g to 5 m²/g, or 6 m²/g, or 7 m²/g, or 8 m²/g, or 9 m²/g; and/or

(iii) a porosity from 0.005 m³/g, or 0.006 m³/g, or 0.008 m³/g, or 0.010 m³/g to 0.012 m³/g, or 0.013 m³/g, or 0.015 m³/g, or less than 0.020 m³/g.

Non-limiting examples of suitable ZnO particles include 800HSA (Zinc Oxide, LLC), ZnO micropowder (US Research Nanomaterials), and Zoco102 (Zochem, Inc.).

(Biii) Particles of Copper Oxide

The odor suppressant also includes particles of copper oxide. The copper oxide can be either “Cu₂O” (copper I oxide) or “CuO” (copper II oxide), or a mix of both. In an embodiment, the copper oxide particles have a D50 particle size from 100 nm to 3000 nm and a surface area from 1 m²/g to less than 10 m²/g. Bounded by no particular theory, it is believed that the copper oxide particles contribute as a sulfur scavenger for hydrogen sulfide and mercaptans in particular.

In an embodiment, the copper oxide particles have a particle size D50 from 100 nm, or 200 nm, or 300 nm, or 400 nm to 500 nm, or 600 nm, or 700 nm, or 800 nm, or 900 nm, or 1000 nm, or 2000 nm, or 3000 nm. Non-limiting examples of suitable copper oxide particles include Cu₂O 325 mesh powder and CuO 325 mesh powder available from Reade Advanced Materials.

C. Composition

The present composition includes (A) from 85 wt % to 99.5 wt % of the olefin-based polymer and (B) from 15 wt % to 0.5 wt % of the odor suppressant, based on total weight of the composition (hereafter, Composition 1). The odor suppressant is mixed, or otherwise blended, into the olefin-based polymer matrix, and is a blend of (Bi) an ionomer, (Bii) particles of zinc oxide, and (Biii) particles of copper oxide. The composition has an odor suppression value of greater than 45%. In an embodiment, the composition has an odor suppression value from 46%, or 49%, or 50% or 60% or 70% to 75%, or 80%, or 85%, or 90%.

The ZnI/O (Bi) is present in component (B) in an amount of 1 to 90 wt % based on the total weight of component (B). The ratio of ZnO to ZnI/O (hereafter “ZnO to ZnI/O ratio”) is from 3:1 to 1:7 based on the total weight of the odor suppressant (B). The ZnO to ZnI/O ratio can be from 3:1, or 2:1, or 1:1 to 1:2, or 1:3, or 1:4, or 1:5, or 1:6, or 1:7. The particles of copper oxide (Biii) are present in component (B) in an amount of from 0.01 wt % to 30 wt % based on the total weight of component (B). The particles of copper oxide can be copper (I) oxide (Cu₂O), copper (II) oxide (CuO), or a mix of both. In an embodiment, the weight percent ratio between the ionomer (Bi), the zinc oxide (Bii), and the copper oxide (Biii) is from 150:100:1 to 2.9:2.5:1 based on the total weight of the odor suppressant (B) (hereafter, Composition 1).

In an embodiment, the weight percent ratio between the ionomer (Bi), the zinc oxide (Bii), and the copper oxide (Biii) is from 100:75:1 to 3:2.5:1 based on the total weight of the odor suppressant (B).

In an embodiment, the present composition includes from 85 wt %, or 90 wt % to 95 wt %, or 97 wt %, 99 wt %, or 99.4 wt %, or 99.5 wt % component (A) that is an ethylene-based polymer. The present composition includes a reciprocal amount of the odor suppressant, component (B), or from 15 wt %, or 10 wt % to 5 wt %, or 3 wt %, 1 wt %, or 0.6 wt %, or 0.5 wt % odor suppressant wherein Zn 1/O to ZnO to Cu₂O ratio is from 12.5:12.5:1 to 2.5:2.5:1. The odor suppressant (B) can be any odor suppressant as previously disclosed herein (hereafter, Composition 2).

The composition (i.e. Composition 1 and/or Composition 2) has an odor suppression value from 46%, or 50%, or 60%, or 70% to 75%, or 80%, or 85%, or 90%.

While the combination of ZnO and ionomer improve OSV for methyl mercaptan, the addition of copper oxide, and in particular Cu₂O, has been observed to further improve overall OSV. In fact, Applicant surprisingly discovered that the addition of from 0.01 wt % to 0.1 wt % of Cu₂O to a ZnO/ionomer odor suppressing composition (based on the total weight of odor suppressant composition (B), for example) can more than double the OSV performance compared to ZnO/ionomer odor suppressing compositions that lack the copper oxide particles.

D. Blend

Components (A) and (B) are mixed, or otherwise blended, together to form the present composition so that the particles of zinc oxide and the particles of copper oxide are (i) dispersed within the olefin-based polymer (A) and/or (i) dispersed within the ionomer (Bi).

In an embodiment, the present composition is produced as an odor control masterbatch wherein component (B) is formed by dispersing the zinc oxide particles (Bii) and the copper oxide particles (Biii) into the ionomer (Bi). The dispersing may be accomplished by physical mixing and/or melt blending of components (Bi), (Bii), and (Biii) in order to uniformly disperse the particles (zinc oxide and copper oxide) throughout the ionomer. The resultant component (B) is subsequently mixed, or otherwise blended, with the olefin-based polymer, component (A). The mixing of component (B) and component (A) may be accomplished by physical mixing and/or melt blending (hereafter odor control masterbatch 1).

In an embodiment, the present composition is produced as an odor control masterbatch by dispersing the zinc oxide particles (Bii) into the ionomer (Bi). The dispersing may be accomplished by physical mixing and/or melt blending of components (Bi) and (Bii) in order to uniformly disperse the zinc particles throughout the ionomer (Bi) (“Bi-Bii blend”). The Bi-Bii blend and the copper oxide particles are subsequently added to the olefin-based polymer component (A) by physical mixing and/or melt blending to form the present composition of a homogeneous blend of olefin-based polymer (A), ionomer (Bi), zinc oxide particles (Bii), and copper oxide particles (Biii). (hereafter odor control masterbatch 2)

In an embodiment, the present composition is produced as an odor control masterbatch by mixing the ionomer (Bi), the zinc oxide particles (Bii), the copper oxide particles (Biii) and the olefin-based polymer (A). The mixing may be accomplished by physical mixing and/or melt blending of components (A), (Bi), (Bii), and (Biii) in order to uniformly disperse the ionomer (Bi), the zinc oxide particles (Bii), and the copper oxide particles (Biii) throughout the olefin-based polymer (A) (hereafter odor control masterbatch 3).

In an embodiment, the present composition is produced as an odor control masterbatch by mixing the ionomer (Bi), the zinc oxide particles (Bii), and the olefin-based polymer (A). The mixing may be accomplished by physical mixing and/or melt blending of components (Bi), (Bii), and (A) in order to uniformly disperse (Bi) and (Bii) throughout (A) (hereafter, A-Bi-Bii blend). Copper oxide particles (Biii) are mixed with component (A). The mixing may be accomplished by physically mixing and/or melt blending in order to uniformly disperse the copper oxide particles (Biii) into (A) (hereafter, A-Biii blend). The A-Bi-Bii blend is then mixed with the A-Biii blend. The mixing may be accomplished by physical mixing and/or melt blending to form a homogeneous composition composed of olefin-based polymer (A), ionomer (Bi), zinc oxide particles (Bii), and copper oxide particles (Biii) (hereafter, odor control masterbatch 4).

In an embodiment, the odor control masterbatch (i.e., any of odor control masterbatch 1, 2, 3, or 4) includes from 20 wt % to 30 wt % ionomer, from 20 wt % to 30 wt % particles of zinc oxide, from 5 wt % to 15 wt % particles of copper oxide, and from 30 wt % to 60 wt % LLDPE, with the aggregate of the components amounting to 100 wt % odor control composition.

E. Applications

The present composition may be used in any application wherein a polymeric material, and an olefin-based polymer in particular, is exposed to mercaptans, H₂S, disulfides or amines. Non-limiting examples of suitable applications for the present composition include trash liners, hygiene articles, poultry diapers, ostomy bags, mattresses, mattress covers, poultry packaging, automotive interior parts, carpet fibers, and carpet backing.

In an embodiment, the composition is formed into a film. The film can be a stand-alone monolayer film. Alternatively, the film can be a layer of a multilayer film. The composition can be any composition as disclosed herein, with component (A) and odor suppressant (B), such as Composition 1 or Composition 2, for example. The film includes the present composition that is an odor control composition, the present composition composed of (A) from 85 wt % to 99.5 wt % of an olefin-based polymer and (B) from 15 wt % to 0.5 wt % of the odor suppressant. The odor suppressant is a blend composed of (i) an ionomer (for example, a zinc ionomer), (ii) particles of zinc oxide, and (iii) particles of copper (I) oxide or copper (II) oxide. The zinc oxide particles have a D50 particle size from 100 nm to 3000 nm, a surface area from 1 m²/g to 9 m²/g, and a porosity less than 0.020 m³/g. The composition has a methyl mercaptan odor suppression value of greater than 45%. In an embodiment, the film has an odor suppression value from 46%, or 50%, or 60%, or 70% to 75% or 80%, or 85%, or 90%.

In an embodiment, the odor control composition formed into a film includes Cu₂O particles that are 325 mesh.

By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.

Examples

Materials used in the examples are provided in Table 1 below.

TABLE 1 Material/Description Properties Source Ethylene/octene 0.9 melt flow rate (I2) (g/10 min) The Dow (LLDPE 1) 0.923 g/cc Chemical Company ZnO 800HSA ZnO D50 particle size 3000 nm; density = 5.61 g/cc; Zinc Oxide, LLC Zinc Oxide Porosity 0.0131 g/m³, surface area 4.46 m²/g micro-powder (ZnO-1) Zinc Oxide ZnO D50 particle size 500 nm; density = 5.61 g/cc; 500 nm (US micro-powder Porosity 0.008 m³/g, surface area 3.36 m²/g Research (ZnO-2) Nanomaterials) Zoco102 ZnO D50 particle size 200 nm; density = 5.61 g/cc; Zochem, Inc. Zinc Oxide Porosity 0.012 m³/g, surface area 4.4 m²/g micro-powder (ZnO-3) Ampacet 110069 70 wt % TiO₂ Ampacet White PE MB in Carrier Resin LLDPE (MI 2.3, d- 0.917 g/cc) Corporation Titanium dioxide Masterbatch Specific gravity: 2.03 (TiO₂) Masterbatch Surlyn ® 9150 Ethylene/Methacrylic Acid Copolymer, zinc cation Dow-DuPont (Zinc Ionomer) Density 0.970 g/cc, melt flow 4.5 g/10 min Cu₂O 325 mesh Reade Advanced Materials

1. Films

Master batch processing. Two master batches were prepared to ease feeding the odor suppressing compositions into a subsequent film line. The master batches were prepared on a Coperion ZSK 26 twin screw extruder using a general purpose screw. The residence time of material was controlled by the screw design, feed rate of 20 lbs/hr, and a screw speed of 300 revolutions per minute (RPM). No oil was injected. There was no side arm feeder. No vacuum was pulled. The compounded material was sent through a water bath before being cut by a strand cut pelletizer. After collection the pelletized materials were N₂ purged, then sealed in an aluminum bag.

The composition of the first master batch (MB1) was 50 wt % LLDPE 1, 25 wt % ZnO, and 25 wt % Suryn 9150. The composition of the second master batch (MB2) was 90 wt % LLDPE 1 and 10 wt % Cu₂O. Examples and counter example formulations were generated using the appropriate amount of pure LLDPE 1, MB1 and MB2 to achieve the target weight % of each composition listed.

TABLE 2 Blown film line process parameters Films without Films containing Parameter Units TiO₂ MB TiO₂ MB Takeoff m/min 15 15 Layflat cm 23.5 23.5 Frostline cm 14 14 B.U.R ratio 2.5 2.5 Die gap mm 2.0 2.0 Melt temperature - Ext. A ° C. 218 218 Melt temperature - Ext. B ° C. 226 226 Melt temperature - Ext. C ° C. 215 215 RPM - Ext. A rpm 51 51 RPM - Ext. B rpm 50 50 RPM - Ext. C rpm 32 32 Total Output kg/hr 8.8 8.8 Film Total Thickness mm 0.023 0.056

2. Odor Suppression

The compositions of comparative samples (CS) and inventive examples (IE) are shown in Table 3.

The odor suppression values (OSV) for are provided in Table 3 below. Concentrations were measured using the reference sample (CS 1) as the calibration standard after two days, concentrations in the reference sample might change after two days, so the concentrations in the samples should be considered as the relative change to the reference sample.

TABLE 3 Odor Suppression Values and Blown Film Properties OSV of Methyl Mercaptan Sample Components Methyl Mercaptan OSV (%) CS 1 99% LLDPE 1 + 1% TiO₂ MB 12 CS 2 97.5% LLDPE 1 + 2.5% TiO₂ MB 2 CS 3 99% LLDPE 1 + 0.5 wt % ZnO + 0.5 wt % Zinc Ionomer 28 CS 4 97.5% LLDPE 1 + 1.25 wt % ZnO + 1.25 wt % Zinc Ionomer 44 IE 1 97.4% LLDPE 1 + 1.25 wt % ZnO + 1.25 wt % Zinc Ionomer + 0.1% Cu₂O 80 IE 2 98.9% LLDPE 1 + 0.5 wt % ZnO + 0.5 wt % Zinc Ionomer + 0.1% Cu₂O 64 IE 3 99.4% LLDPE 1 + 0.25 wt % ZnO + 0.25 wt % Zinc Ionomer + 0.1% Cu₂O 49 Zinc ionomer used in Table 3 is Surlyn ® 9150 *TiO₂ MB—titanium dioxide masterbatch 70 wt % TiO₂ powder in 30 wt % LLDPE carrier, added for white color

In Table 3, component amounts for each sample yield 100 wt % total sample composition. It can readily be observed that the ZnO/zinc ionomer combination is effective in improving OSV as compared to a composition that lacks any odor suppressing technology by comparing the OSV for CS 3 (28%) to the OSVs for CS 1 & 2 (12% and 2% respectively). However, it is surprising to see that although Cu₂O is added at very low loadings as part of the present odor suppressant (i.e., at <10% of the combination of ZnO, zinc ionomer, and Cu₂O in IE2), it can further improve the OSV to 64% as compared to CS 3 OSV of 28%, (i.e., the sample with zinc ionomer and ZnO, and without Cu₂O present). The addition of Cu₂O unexpectedly allows for a reduction in ZnO/zinc ionomer concentrations by 50% in the composition while maintaining an OSV that is almost 50% higher than the ZnO/zinc ionomer combination that does not have Cu₂O present, as can be observed by comparing the OSV for IE3 (49%) to the OSV of CS3 (28%). It is further observed that the ZnO/zinc ionomer combination still exhibits a significant influence on OSV in that higher loadings of these materials in combination with 0.1 wt % Cu₂O exhibits the highest OSV of the inventive examples IE1 (80%) and IE2 (64%) shown in Table 3.

It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. 

1. A composition comprising: (A) from 85 wt % to 99.5 wt % of an olefin-based compound; (B) from 15 wt % to 0.5 wt % of an odor suppressant comprising a blend of (i) an ionomer; (ii) particles of zinc oxide; (iii) particles of copper oxide; and the composition has a methyl mercaptan odor suppression value of greater than 45% as measured in accordance with ASTM D5504-12.
 2. The composition of claim 1, wherein the olefin-based polymer is an ethylene-based polymer.
 3. The composition of claim 2, wherein the ethylene-based polymer is an ethylene/C₄-C₈ α-olefin copolymer having a melt index (I₂) from 0.5 g/10 min to 15 g/10 min and a density of 0.910 g/cc to 0.930 g/cc.
 4. The composition of claim 1, wherein the ionomer is a metal ionomer.
 5. The composition of claim 1, wherein the ionomer is a zinc ionomer.
 6. The composition of claim 5, wherein the ionomer is a zinc salt of a polymer selected from the group of ethylene/methyl-methacrylic acid, ethylene/vinyl acrylic acid, ethylene/methacrylate, ethylene/n-butyl acrylic acid, and ethylene acrylic acid.
 7. The composition of claim 1, wherein the particles of zinc oxide have a D50 particle size from 100 nm to 3000 nm.
 8. The composition of claim 1, wherein the particles of copper oxide are selected from the group of copper (I) oxide and copper (II) oxide.
 9. The composition of claim 8, wherein the particles of copper oxide have a D50 particle size from 100 nm to 3000 nm.
 10. The composition of claim 1, wherein the weight percent ratio between the ionomer (Bi) the zinc oxide (Bii) and the copper oxide (Biii) is from 150:100:1 to 2.9:2.5:1.
 11. A film comprising: a composition comprising: (A) from 85 wt % to 99.5 wt % of an olefin-based compound; (B) from 15 wt % to 0.5 wt % of an odor suppressant comprising a blend of (i) an ionomer; (ii) particles of zinc oxide; (iii) particles of copper oxide; and the composition has a methyl mercaptan odor suppression value of greater than 45% as measured in accordance with ASTM D5504-12. 